Utilizing microlevel data in the form of reconstituted family histories from the unique village genealogies for Germany, preindustrial population dynamics and the transition to modern patterns of demographic behavior are being explored. Four villages will be studied intensively with respect to a wide variety of demographic behavior and a larger number will be studied selectively with respect to natural fertility, the emergence of family limitation and the relationship between child mortality and reproductive patterns. The analysis will give special attention to temporal change. Because the data are micro-level, they permit direct estimation of the "Physiological" and "replacement" efforts of child mortality on fertility. Particularly valuable is the opportunity for exploring changes in this relationship during the demographic transition. The influence of birth interval length, family size, and parity on mortality risks of offspring will also be examined. Another focus will be natural fertility and family limitation with special attention to evidence of control prior to the fertility decline and the transformation from pre-industrial to modern childbearing patterns. The data permit an individual level analysis not possible with the aggregate data used in previous studies of the demographic transition. Other aspects of demographic behavior under investigation include illegitimacy, bridal pregnancy, marriage and remarriage. The data permit exploring generational links in illegitimacy and its consequences for the mother's marriage prospects and the life chances of the children. Changes in illegitimacy and nuptiality can be related to the establishment and repeal of restrictive marriage legislation. Occupational differentials in illegitimacy and bridal pregnancy should shed light on secular changes in sexual behavior.